Brief.
We have made a fix in Search Engines settings after release 2.8 has been issued.
All fresh installs starting from release 3.0 don't contain this bug.
 
Description.
There was a bug like:
PHP Warning: preg_match() [<a href='function.preg-match'>function.preg-match</a>]: Unknown modifier 'T' .../includes/va_functions.php on line 273
Provided fix corrects table va_search_engines.
 
Solution.
Please download a fix from here
http://www.viart.com/downloads/va_fix_engines-2.8.zip
Then extract file va_fix_engines.php into the root folder of your shop and execute it in the browser - visit this page like http://your.domain.com/va_fix_engines.php
Delete va_fix_engines.php from the root folder after all.